Calculate electrical box volume needed

Question

I am replacing some 15A 14/2 outlets.  All went fine except the last.  I think the box is not large enough.

(3) 14/2 coming into the box; one is the live the other two go to other outlets
All grounds in a wire nut, single ground going to outlet ground.
2 of the hot from the outgoing are connected via wire nut, single hot going into the push pin connector
hot from the live in the other push pin
the 3 neutrals are in the two push pins and the screw connector (no wire nut used)

How do I count this?  I'm pretty sure the 3x2x2.5 box is not enough.

Ecnerwal · Accepted Answer

All grounds count 1. (per @ThreePhaseEel's comment, more than 4 are now 1/4 count each as of NEC2020)
One yoke device (the outlet) is 2
6 wires terminating in the box are 6
If there are cable clamps in the box, those count as 1. If they are outside the box, they don't count.
14Ga so 2 cubic inches per count.
So: 18 or 20 cubic inches. Pigtails (wires that don't leave the box) are free. Wires count the same if they terminate on a wire nut or terminate on a device.  Your box isn't big enough, you are correct about that. A box can be legit and still be hard to pack in (the free things are not really free that way) but the box you have is not legit as wired.
Side note. Using the backstabs is highly dubious and frowned upon by anyone who has removed a half-melted device using them, or actually had a fire started by them. How they ever got approval is beyond me. Use the side screw clamps or devices that have a screw clamp on a different type of back wire entry.

Calculate electrical box volume needed

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